1. Field of the Invention
The disclosed embodiments relate generally to electronic devices with a display operable to scroll a virtual display of contents which may be larger than the actual size of the device's physical display.
2. Description of the Related Art
Hand held devices with a small physical display must often show a virtual stored or computed contents display that is larger than the screen view of the physical display. Only a portion of the virtual display can be shown at any given time within the screen view, thus requiring an interactive process of view navigation that determines which particular portion of the virtual display is shown. This process must allow the user to scroll the entire virtual display. Various methods have been used to control view navigation, including keyboards, joysticks, touch screen gestures, voice commands, rotational and movement sensors, and visual gestures.
Today's most popular user interface in hand held devices is the touch screen display. The touch screen display enables the user to perform single-touch and multi-touch gestures (also called “touch commands”) to navigate (or “scroll”) the display as well as to activate numerous functions and links. The versatility of these touch screen gestures caused the gradual disappearance of traditional means of view navigation like keyboards and joysticks.
As a result, most contemporary mobile devices employ the Flick and the Drag (panning) touch screen gestures to control the view navigation process. These gestures normally require cumbersome, two-hand operation as the user holds the device with one hand and performs the gesture with the other. These touch gestures may cause unhealthy ergonomic strains on users, particularly when the user attempts to perform a single hand Flick gesture. Even if the user is somehow able to perform touch commands with only one hand, the fingers that touch the screen are still always in the way, obstructing the screen view. Touch screen gestures often cause unintended activation of links that may be present on the screen during scrolling, and result in fingerprints and dirt being left on the screen. When the virtual display size is much larger than the screen size, many repeated touch screen commands are necessary for scrolling the contents.
Various methods have been proposed as an alternative to touch screen commands for performing screen scrolling. A promising alternative is a view navigation system based on motion, which allows the users to scroll the display using only one hand and without obscuring the screen view by the fingers that are used for touch commands. In this disclosure, the term ‘motion’ refer to device motion that can be translated into a rotation (or tilt) change relative to a given baseline. This view navigation system of a mobile device may utilize a set of rotation and movement sensors like the gyroscope, tilt sensor, camera tilt detector, magnetic sensor, Infra Red multiple camera rotation sensor, and any combination of these sensors.
An early motion-based view navigation system is disclosed in my U.S. Pat. Nos. 6,466,198 and 6,933,923 which are incorporated by reference herein in their entirety. These patents have been commercialized under the trade name “RotoView” and their development has been chronicled online at http://www.rotoview.com. The “RotoView” system is well adapted to navigate the device's screen view across an arbitrarily large contents view. Among other features, “RotoView” introduced the fixed mode and navigation (e.g. scrolling) mode so that the screen view does not continue to follow the tilt changes when the view navigation system is brought back to the fixed mode at the end of the scrolling mode. Another “RotoView” feature is its ability to provide various fine and coarse modes of scrolling. At the fine scrolling mode, relatively large tilt (or “orientation”) changes cause only a small amount of scrolling. Conversely, at the coarse scrolling mode, relatively small tilt changes cause large amounts of scrolling.
A motion-based view navigation system works in a closed control loop between the user and the device, where the user iterates the rotational motion in response to the actual scrolling occurring on the screen. If a motion-based scrolling device is first rotated beyond the edge of the contents view and then rotated back, the user experiences an undesired range of no response to the back rotation. If the rotation beyond the edge is significant, the undesired non-responsive range of rotation is quite large, during which the closed control loop between the user and the device is temporarily broken, as the user perceives no responses while changing the tilt of the device.
It should be noted that the user gains the best viewing experience when the screen surface is held perpendicular to her eyes. An often encountered challenge in motion-based view scrolling system is the viewing quality experienced during the tilting of the device, when the device is held at an oblique angle to the line of sight.
Therefore, it would be desirable to provide methods and systems that can reduce or eliminate the above deficiencies and improve the user's experience during motion-based view scrolling. Such methods should also reduce the cognitive burden on the user and produce a more efficient user interface that is intuitive and easy to use.